Radio frequency (RF) power amplifiers (PA) typically constitute a core of RF systems such as front-end modules (FEM) that provide up-converted signal transmission over the air in wireless telecommunications by amplifying a signal supplied by a radio and fed to an antenna. Typically, the antenna has a 50 Ohm impedance at the transmit frequency. Within the FEM, the power amplifier is required to be matched to the antenna impedance, (e.g. 50 Ohm). In order to deliver a required RF power to the antenna, the PA has to be presented with correct load impedance. The transformation of the antenna impedance to the necessary PA load impedance is typically done using passive components, such as capacitors and inductors, monolithically integrated or in discrete form as will be addressed later in this specification. The output impedance transformation network, in addition to the impedance matching, is also required to perform a filtering function to reduce out-of-band spurious signals, whose levels are guided by Federal Communications Commission (FCC) regulations. Typically, a filter is incorporated to enhance spurious signal suppression. The total loss of the network is the combination of the losses experienced by the PA and the filter plus the loss due to the impedance transformation network. Total post PA loss inside the FEM adversely affects the DC power consumption, and thus the Power
Added Efficiency (PAE).
There is a need for an FEM that lowers the overall post PA output loss by 1 dB-1.5 dB, improves DC power consumption by 20-40%. provides robust (temperature and process stable) out-of-band signal filtering, achieves lower system operating temperature, and achieves a smaller overall FEM size.